U.S. patent number 5,427,552 [Application Number 08/155,506] was granted by the patent office on 1995-06-27 for electrical terminal and method of fabricating same.
This patent grant is currently assigned to Chrysler Corporation. Invention is credited to Gregg A. Eisenmann, Robert D. Kennedy, Nickolas O'Branovic, Sucha S. Sian, Thomas E. Zielinski.
United States Patent |
5,427,552 |
Zielinski , et al. |
June 27, 1995 |
Electrical terminal and method of fabricating same
Abstract
A female electrical terminal element for connecting a wire lead
to a male contact pin has a first end which is crimped to the wire
lead and a second end in the form of a socket. The socket includes
a cantilevered contact floor and a unitary separate spring contact
in opposed relation to the cantilevered contact floor. The male
contact pin is inserted between the spring biased contact surface
and the cantilevered contact floor to establish an electrical
connection. In order to improve the reliability and current
carrying capacity of the female component, the cantilevered contact
floor is supported at a bight portion thereof while the contact
floor is being bent through 180.degree.. After the cantilevered
contact floor is bent 180.degree., the side flanges of the female
component are folded over to make an enclosure for defining the
socket and retaining the unitary spring contact in the socket.
Inventors: |
Zielinski; Thomas E. (China,
MI), Eisenmann; Gregg A. (Canton, MI), Kennedy; Robert
D. (Northville, MI), O'Branovic; Nickolas (Royal Oak,
MI), Sian; Sucha S. (Southfield, MI) |
Assignee: |
Chrysler Corporation (Highland
Park, MI)
|
Family
ID: |
22555720 |
Appl.
No.: |
08/155,506 |
Filed: |
November 22, 1993 |
Current U.S.
Class: |
439/845; 439/849;
439/850 |
Current CPC
Class: |
H01R
13/187 (20130101); H01R 43/16 (20130101); Y10T
29/49218 (20150115); Y10T 29/49222 (20150115) |
Current International
Class: |
H01R
13/15 (20060101); H01R 13/187 (20060101); H01R
43/16 (20060101); H01R 013/00 () |
Field of
Search: |
;439/843,845,847,849,850,852,857,859,858,861 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
|
|
|
|
313253 |
|
Apr 1989 |
|
EP |
|
1427747 |
|
Jan 1966 |
|
FR |
|
Primary Examiner: Briggs; William
Attorney, Agent or Firm: Fredericks; Wendell K.
Claims
What is claimed is:
1. A female electrical terminal comprising:
means at a first end for crimping a wire lead thereto;
a second end in the form of a socket for receiving a male contact
pin, the socket including a front base portion and a cantilevered
contact floor which is unitary with the front base portion and
joined thereto by a bight, the contact floor being formed by
folding the contact floor while engaging the bight with a
supporting surface, the contact floor having a free end and a pair
of longitudinally extending peripheral foot flanges projecting
toward the front base portion and depending from side edges of the
contact floor; and
a spring biased contact disposed within the socket in opposed
relation to the cantilevered contact floor for urging the male
contact pin into abutment with the cantilevered contact floor.
2. The terminal of claim 1, wherein the cantilevered contact floor
includes a pair of parallel, spaced ribs extending in a direction
away from the foot flanges, the ribs being formed by embossments
which extend from the bight toward the free end of the cantilevered
contact floor.
3. A female electrical terminal comprising:
means at a first end for crimping a wire lead thereto;
a second end in the form of a socket for receiving a male contact
pin, the socket including side walls with windows therethrough, a
top wall having an abutment extending into the socket, a front base
portion and a cantilevered contact floor which is unitary with the
front base portion and joined thereto by a bight, the contact floor
being formed by folding the contact floor while engaging the bight
with a supporting surface; and
a separate, unitary contact spring disposed within the socket in
opposed relation to the cantilevered contact floor for urging the
male contact pin into abutment with the cantilevered contact floor,
the separate unitary spring contact having lateral extending tabs
which engage windows in the side walls and an end edge which
engages the abutment extending into the socket from the top
wall.
4. The electrical terminal of claim 3, wherein the contact floor
has a free end and a pair of longitudinally extending peripheral
foot flanges projecting toward the front base portion and depending
from side edges of the contact floor.
5. The electrical terminal of claim 4, wherein the cantilevered
contact floor includes a pair of parallel, spaced ribs extending in
a direction away from the foot flanges, the ribs being formed by
embossments which extend from the bight toward the free end of the
cantilevered contact floor.
Description
FIELD OF THE INVENTION
The present invention relates to an electrical terminal and to a
method for fabricating that terminal. More particularly, the
present invention relates to an electrical terminal and a method of
fabricating that terminal wherein the terminal is a female terminal
utilizing a contact spring to urge an inserted male contact blade
into contact with a contact floor which is unitary with the female
terminal.
BACKGROUND OF THE INVENTION
As automobiles increasingly rely on electrical components, the
number of electrical terminals necessarily increases. In that the
electrical components interact with one another, it is increasingly
important that electrical connections be properly made so that each
contact carries the current load which it is expected to transmit.
In automobiles, electrical connections are frequently subjected to
impacts and vibration due to the motion and vibration caused by
both vehicular motion and engine operation. In addition, since many
electrical components are proximate the engine of a vehicle, the
components are subjected to heat. Moreover, moisture and road dirt
can over time invade electrical terminals when from time to time
the terminals are disconnected for maintenance purposes.
Preferably, electrical terminals should maintain good contact when
connected, while allowing the terminals to be easily both initially
connected, and subsequently disconnected and then reconnected,
perhaps a number of times. Over time, many currently available
electrical may terminals fail to continuously transmit adequate
current and, from time to time, may fail when being disconnected
and reconnected.
It is also highly desirable to maximize the current carrying
capacity of electrical terminals so that their physical size may be
minimized as well as their number.
SUMMARY OF THE INVENTION
In view of the aforementioned considerations, it is a feature of
the instant invention to provide a new and improved electrical
terminal in which a good, reliable electrical connection is
maintained over a time with periodic disconnections and
reconnections, which does not fail during either the fabrication
process or upon initial coupling and which has increased current
carrying capacity.
In view of this feature and other features, the present invention
is directed to a female electrical terminal element having means at
one end for crimping a wire lead thereto and a second end in the
form of a socket for receiving a male contact pin. The socket
includes a cantilevered contact floor which is unitary with the
socket and is formed by folding the cantilevered contact floor
about a bight while maintaining support at the bight. A separate
spring biased contact is disposed within the socket in opposed
relation to the cantilevered contact floor for urging the male
contact blade into abutment with the cantilevered contact
floor.
The instant invention is also directed to a method for forming a
female electrical terminal component which is affixed at one end to
a wire lead and which has a female socket at the other end for
receiving a male contact blade urged into abutment with a portion
of the socket by a contact spring. In accordance with the method,
the female component is formed from a unitary blank by folding a
pair of side flanges to extend substantially normal with respect to
a base portion to form a channel. A cantilevered contact floor is
then folded about a bight, while in alignment with the channel, to
overlie the base portion. While the cantilevered contact floor is
being folded, it is supported at the bight. The side flanges are
then bent so that free ends thereof overlie the contact portion in
spaced relation with respect thereto to form the socket .
BRIEF DESCRIPTION OF THE DRAWINGS
Various other objects, features and attendant advantages of the
present invention will be more fully appreciated as the same
becomes better understood when considered in conjunction with the
accompanying drawings, in which like reference characters designate
the same or similar parts throughout the several views, and
wherein:
FIG. 1 is a side elevation illustrating a female electrical
terminal in accordance with the instant invention crimped at one
end to a wire lead and detachably connected at the other end with a
contact blade of a male terminal;
FIG. 2 is a perspective view of the female electrical terminal with
portions partially bent and with portions in phantom;
FIG. 3 is a top view of a strip with a plurality of female terminal
blanks extending therefrom in various stages of fabrication;
FIG. 4 is an enlarged top view showing a cut blank from which the
female electrical terminal is formed by bending;
FIG. 5 is an enlarged side view showing side flanges bent upward
and a cantilevered contact floor being bent upward;
FIG. 6 is a view similar to FIG. 5 showing the contact floor bent
to a final position;
FIG. 7 is a view of a prior art contact floor;
FIG. 8 is a side elevation showing die faces holding the blank and
advancing to fold the cantilevered contact floor to a first
position in a first bending step;
FIG. 9 is a view similar to FIG. 8 and showing second die faces
folding the cantilevered contact floor to a second position in a
second bending step;
FIG. 10 is a view similar to FIGS. 8 and 9 showing third die faces
bending the cantilevered contact floor to a third position in a
third bending step;
FIGS. 11 and 12 are views similar to FIGS. 8-10 showing the
cantilevered contact floor being bent to a fourth position in a
fourth bending step;
FIG. 13 is a view similar to FIGS. 11 and 12 showing the dies
releasing the finally formed cantilevered contact floor;
FIG. 14 is a side elevation of the female terminal after side
flanges have been folded over to form a socket;
FIG. 15 is a front view of the assembled female terminal; and
FIG. 16 is an enlarged, perspective view of the assembled female
terminal receiving the contact pin of a male terminal.
DETAILED DESCRIPTION
Referring now to FIGS. 1 and 2, there is shown a female electrical
terminal 10 for connecting an electrical wire lead 12 to a male
contact blade 14. The female electrical terminal 10 retains the
wire lead 12 by first and second pairs of crimp flanges 16 and 18
which are crimped over the wire lead 12 and its insulation 19,
respectively, at a first end 20 of the female terminal. At a second
end 22 of the female terminal 10, there is disposed a socket 24
having a spring biased contact surface 26 therein. The spring
biased contact surface 26 is unitary with, and biased by, a bowed
or leaf steel spring contact 28 having two arms 29 and 30 which
urge the contact surface 26 into abutment with the male contact pin
14. Beneath the male contact pin 14 is a cantilevered contact floor
31. The leaf spring contact 28 is in part longitudinally retained
by an abutment 32 extending from the top wall of the abutment 32
extending from the top wall of the socket 24, a short distance into
the socket and engages and end edge 33 of the leaf spring contact
when the leaf spring contact is stressed.
In an electrical terminal of the type illustrated in FIGS. 1 and 2,
80%-90% of the current flows through the cantilevered contact floor
31 into the body of the female electrical terminal 10 so as to be
transmitted through to the wire lead 12 via the crimp 18 and a rear
bottom surface 34 of the first end 20 of the terminal 10. It is
therefore very important that the electrical terminal contact
surface between the male contact blade 14 and the cantilevered
contact floor 31 be adequately maintained and not deteriorate over
time due to various mechanical and environmental factors. Moreover,
it is important that cantilevered contact floor 31 transmit as much
current as possible. Therefore, it is desirable that the current
carrying capacity of the cantilevered contact floor 31 not be
diminished during fabrication.
Referring now to FIG. 4, there is shown a strip 40 having a
plurality of the female electrical terminals 10 mounted thereon for
folding by the fabrication machinery of FIGS. 8-13. As the strip 40
is advanced, various unitary sections of the female electrical
terminal 10 are folded over one another so that the female terminal
is ready to receive the wire lead 12 (FIG. 1), the spring biased
contact 26 (FIG. 1) and ultimately the male contact pin 14 (FIG.
1).
Referring now to FIG. 4 wherein the female electrical terminal 10
is shown enlarged as a blank 41 before folding, it is seen that the
second end 22 which is folded to form the socket 24 for receiving
the male contact pin blade 14 includes first and second side
flanges 44 and 46. The first and second side flanges 44 and 46 each
include, respectively, windows 48 and 50 as well as embossments 52
and 54 which form raised shelves. Inboard of the embossments 52 and
54, a large window 56 is disposed in a front base portion 57 of the
terminal 10. Between the large window 56 and shelves 52 and 54 are
fold areas 58 and 60 which, as is seen in FIGS. 5 and 6, allow the
side flanges 44 and 46 to be bent up out of the plane of the
terminal blank shown in FIG. 4.
In order to facilitate bending, the flanges 44 and 46 have leading
edges 62 and 64 and trailing edges 66 and 68. The leading edges 62
and 64 also intersect with a fold line 70 which extends
perpendicular to the fold lines 58 and 60 so as to allow the
cantilevered contact floor 31 to fold approximately 180.degree.
over the front base portion 57 of the female terminal 10 in
overlying relation to the large window 56 (see FIG. 1). The
cantilevered contact floor 31 has a bottom surface 72 having a pair
of longitudinally extending feet or foot flanges 74 and 76
extending substantially perpendicularly therefrom (see FIGS. 2 and
15). The cantilevered contact floor 31 also has a pair of
contacting ribs 77 and 78 which are formed therein by embossing the
contact floor before it is folded. The contact ribs 77 and 78
extend longitudinally on the contact floor 31 and have flattened
shallow portions 79 proximate fold line 70. When the female
terminal 10 is assembled, the contacting ribs 77 and 78 contact the
male contact pin 14 (see FIG. 1).
In FIG. 5, the cantilevered contact floor 31 and the side flanges
44 and 46 are bent upwardly from the front base portion 57 and in
FIG. 6, the cantilevered contact floor is bent to overlie the
contact front base portion. If the cantilevered contact floor 31 is
bent from the position of FIG. 4, through the position of FIG. 5 to
that of FIG. 6, then the bight 80 of the resulting U-shaped
configuration is subject to "orange peeling" due to stress cracks
rather randomly formed as the cantilevered contact floor 31 is
bent. These random cracks substantially reduce the amount of
current that the terminal can carry. By employing features of the
present invention, as is set forth in FIGS. 8-13, orange peeling is
substantially avoided and the current carrying capacity of the
entire terminal 10 is enhanced.
In order to facilitate the steps shown in FIGS. 8-13, the terminal
of the present invention is configured differently from the
terminal of the prior art shown in FIG. 7, wherein a tab 81
projects downwardly from the cantilevered contact floor 31' and
engages the front base portion 57'. The tab 81 prevents the bight
portion 80' of the prior art cantilevered contact floor 31' from
being supported internally as it is bent and therefore results in a
terminal with stress cracks at the bight which lower the current
carrying capacity of prior art terminals. The cantilevered contact
floor 31 of the present invention has a free end instead of an end
with a tab. In the present invention, the feet 74 and 76 extend
from the sides of the contact floor 31 toward the front base
portion 57.
Referring now to FIG. 8 where the blank 41 of the terminal 10 (also
see FIGS. 3 and 4) is shown being bent in accordance with the
principles of the instant invention, it is seen that the blank 41
is supported on a die shoe 90 having a flat surface 92 for
supporting the blank 41. A die punch 92 with a flat surface 94
retains the blank 41 against the die shoe 90. The die punch 92 has
an overhanging projecting portion 96 which projects beyond a die
surface 98 on the die shoe 90. The die punch also includes a
forming surface 100 which projects at a 60.degree. angle with
respect to the blank 41 or a 120.degree. angle with respect to the
surface 94. In order to being folding the cantilevered contact
floor 31, a first die 102 is advanced in the direction of an arrow
104 to engage and bend the cantilevered contact floor with an
angled surface 108. The angled surface 108 also extends at
60.degree. with respect to the extent of the blank 41 and includes
a section 110 joined to the surface 105 by a corner 111. The die
punch 92 has a width which is less than the space between the feet
74 and 76 of the cantilevered contact floor. As the first die 102
bends the contact floor at a location 112 juxtaposed with the
corner 114 on the die punch 92 and the corner 116 on the first die
face 102, the feet 74 and 76 straddle the surface 100. The first
bend is about 60.degree. so that the cantilevered contact floor 31
is at an angle of about 120.degree. with respect to the front base
portion 57 of the blank 41.
Referring now to FIG. 9, where the blank 41 is shown after the
120.degree. bend in the cantilevered contact floor 31 is introduced
by the step of FIG. 8, the blank 41 is supported by the die shoe 90
and also by a second die punch 120 which now clamps the blank 41
further outboard of the die shoe. The die punch 120 has a die punch
surface 122 which is perpendicular to a bottom surface 124 opposed
to the upper surface 92 of the die shoe 90 and includes a curved
corner 124 around which the bend 126 in the blank 41 is formed.
Opposing the die punch 120 is a second die 130 having a die face
132 parallel to the surface 124 of the die punch and a die face 134
perpendicular to the die face 132. The two die faces are joined by
a curved die corner 136 which complements the curved die corner 124
on the die punch 120 as the second die 130 moves in the direction
of the arrow 138 to bend the cantilevered contact floor 31
substantially normal to the floor portion 57 of blank 41. A land
140 projects from the die face 134 to provide space for
accommodating the thickness t on the cantilevered contact floor 31.
Again, the die punch 120 has a width which fits between the feet 74
and 76 on the cantilevered contact floor 31. The second bend is
about 30.degree. so that the cantilevered contact floor 31 is at
about 90.degree. to the front base portion 57 of the blank 41.
Referring now to FIG. 10, the blank 41 is shown with the
cantilevered contact floor 31 extending perpendicular to the front
base portion 57 of the blank 41 after being bent in accordance with
the step of FIG. 9. In FIG. 10, the blank 41 is still supported by
the die shoe 90; however, a mandrel 150, having a triangular
projection 152 with a 30.degree. face 154 and a bottom face 156, is
used to bend the cantilevered contact floor 31 about a curved nose
158. The mandrel 150 travels in the direction 160. A third die 164
has a first horizontal die face 166 and an angled die face 168
disposed at 60.degree. with respect to the face 166, the die faces
166 and 168 being joined by an arcuate bight 170. The third die 164
advances in the direction of arrow 172 toward the mandrel 150,
while the mandrel advances toward the die 164 in the direction of
arrow 173. The curved faces 158 and 170 bend the blank 41 at area
174 which forms the bight 80 so as to assume the 30.degree. bend of
FIG. 11. The third bend is therefore about 60.degree..
Referring now to FIG. 11, a die shoe 180 now has a configuration
wherein a first flat supporting surface 182 supports the blank 41
and is joined by a second surface 184 which is substantially
parallel to the first surface 182. The second flat surface 184
joins the first surface with a concave surface 186. The bight
portion 80 of the blank 41 is urged against the concave curved
portion 186 by a second mandrel 190 which has a curved nose portion
192 that complements the curvature of both the curved die portion
186 and the bight 80 of the blank 41. A die punch 190 has a first
flat 192 in opposition to the flat 182 on the die shoe 180 and a
second flat 194 in opposition to the second flat 184 in the die
shoe. The flats 192 and 194 are joined by concave curve 196. In
operation, the die punch 196 advances in the direction of arrow 200
toward the die shoe to bend the cantilevered contact floor about
30.degree. so that it extends substantially parallel with the front
base portion 57.
As is seen in FIG. 12, the die punch 190 bends the cantilevered
contact floor 31 over so that it extends substantially parallel to
the front base portion 57 of the blank 41. As this final bend is
performed, the cantilevered contact floor 31 is supported by the
curved nose 192 of the mandrel 190.
As is seen in FIG. 13, the die punch 196 is then raised in the
direction of arrow 202, while the mandrel 190 is withdrawn in the
direction of arrow 204. In that the bight 80 joining the
cantilevered contact floor 31 to front base portion 57 has been
substantially supported during the entire formation of the bend
disposing the cantilevered contact floor substantially parallel to
front base portion 57 of the blank 41, the resulting bight results
in a female terminal 10 which has enhanced reliability.
As was previously stated, this is readily apparent because the
orange peeling which occurs at the bight 80 when the cantilevered
contact floor 31 is not formed with support at the bight, no longer
occurs. It is of utmost importance that the contacting ribs 77 and
78 of the cantilevered contact floor 31 remain, many times for
years, in abutment with a male contact pin 14 under the urging of
the contact spring 26 (see FIG. 1).
As is perhaps best seen in FIG. 1, the spring arms 29 and 30 have
relatively small contact areas with the surfaces of the folded
flanges 44 and 46 compared to the relatively large contact area
provided by the contacting ribs 78 and 79 of the cantilevered
contact floor 31. If the bight portion 80 of the cantilevered
contact floor 31 fractures or develops cracks due to the bending of
the contact floor during fabrication, then its efficiency for
transmitting current is reduced. If the actual connecting area is
substantially reduced, then the current flowing around the bight
portion 80 may be channeled through metal of small cross-sectional
area. This can result in these cross-sectional areas heating and,
after a time, rupturing.
It has been found that up to 90% of the current flows through the
cantilevered contact floor 31 and that, in a terminal made of
copper alloy having a length of about 3/4 inch or 2 cm, a width of
about 1/8 inch (0.5 cm) and a height of about 3/32 inch (0.2 cm),
up to 50 amps of current is successfully conducted under ambient
conditions and 40 amps of current successfully conducted without
failure under shock conditions. This results in a terminal 10 which
is under-rated at 25 amps. The prior art terminals have a shock
rating of about 25 amps and are underrated at 5-20 amps. When such
terminals conduct only 20 amps, then there may be an increased risk
of failure if the shock rating is only 25 amps. Accordingly, either
many more terminals, or terminals of a larger size, are required in
automotive installations when using the prior art terminals. Making
terminals larger or using more terminals results in inherent design
disadvantages over using smaller or fewer numbers of terminals.
Referring now to FIG. 14, after the floor portion 31 has been bent
to the position of FIGS. 13 and 14, the contact spring 26 is
mounted between the upstanding side flanges 44 and 46 which form
side walls. After the contact spring 26 is inserted, flanges 44 and
46 are bent over, as is seen in FIGS. 1, 2 and 14, to form the
socket 24. The flanges 16 and 18 are then bent over for crimping to
the wire lead 12 (see FIG. 1).
As is seen in FIG. 15, the spring arms 29 and 30 of the contact
spring 26 have tabs 220 and 222 which laterally extend through the
small windows 40 and 50, respectively, to retain the spring arms.
The spring arms are additionally supported on the shelves 52 and
54. The side flanges 44 and 46 which form side walls are then again
folded at fold lines 230 and 232 so that upper portions 234 and 236
of the side flanges which form top walls overlie the unitary,
spring contact surface 26 and retain the contact surface and its
associated spring arms 29 and 30 within the socket 24. The spring
through holes 40 and 50 keeps it from being pulled out as a blade
is removed. The end flanges protect the spring from being
overstressed. A pair of end flanges 238 and 240 on the top portions
234 and 236 of the side flanges 44 and 46 form an abutment which
engage the spring arm 28 so that the unitary, spring contact
surface 26 does not slide out of the socket 24 when the male
contact pin 14 is withdrawn therefrom.
Referring now to FIG. 16, there is shown an enlarged view of the
fabricated and assembled female terminal 10 receiving the male
contact pin 14 to connect the male contact pin to the wire lead 12.
An example of the entire female terminal 10 has a length of about
3/4 inch (2 cm), a width of about 1/8 inch (0.5 cm) and a height of
about 3/32 inch (0.2 cm).
From the foregoing description, one skilled in the art can easily
ascertain the essential characteristics of this invention, and
without departing from the spirit and scope thereof, can make
various changes and modifications of the invention to adapt it to
various usages and conditions.
* * * * *